The quest for happiness sends millions of people into bookstores, doctors' offices and pharmacies — especially at this time of year, when well-being seems to be a national requirement.

Of course, the pursuit of happiness is relatively new to humankind — our ancestors were much too focused on their day-to-day survival to spend much time contemplating contentment — but scientists and writers have worked to fill the void in the last few decades, flooding the marketplace with theories and checklists. (See "The Happiness Hypothesis: Finding Modern Truth in Ancient Wisdom" by Jonathan Haidt, or "Stumbling on Happiness" by Daniel Todd Gilbert or "Every Day a Friday: How to Be Happier 7 Days a Week" by Joel Osteen.)

When author Gretchen Rubin examined happiness, she thrust her entire being into the project. But rather than chase the latest self-help bestsellers, Rubin decided to write her own — bestsellers, that is.